Apparatus for negative-pressure therapy and irrigation

ABSTRACT

Systems, methods, and apparatuses for irrigating a tissue site are described. The system can include a tissue interface and a sealing member configured to be placed over the tissue site to form a sealed space, and a negative-pressure source fluidly coupled to the sealed space. The system includes an irrigation valve having a housing, a piston disposed in the housing, a fluid inlet to fluidly couple a fluid inlet chamber to a fluid source, and a fluid outlet to fluidly couple a fluid outlet chamber to the sealed space. A piston passage extends through the piston and fluidly couples the fluid inlet chamber and the fluid outlet chamber, and a biasing member is coupled to the piston to bias the irrigation valve to a closed position. The negative-pressure source is configured to move the piston between the closed position and an open position to draw fluid to the sealed space.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/580,756, entitled “Apparatus for Negative-Pressure Therapy andIrrigation,” filed Dec. 8, 2017, which is a 371 National Stage ofInternational Patent Application No. PCT/US2016/039610, entitled“Apparatus for Negative-Pressure Therapy and Irrigation,” filed Jun. 27,2016, which claims the benefit, under 35 USC 119(e), of the filing ofU.S. Provisional Patent Application No. 62/186,093, entitled “Apparatusfor Negative-Pressure Therapy and Irrigation,” filed Jun. 29, 2015, allof which are incorporated herein by reference for all purposes.

TECHNICAL FIELD

The invention set forth in the appended claims relates generally totissue treatment systems and more particularly, but without limitation,to an apparatus for negative-pressure therapy and irrigation.

BACKGROUND

Clinical studies and practice have shown that reducing pressure inproximity to a tissue site can augment and accelerate growth of newtissue at the tissue site. The applications of this phenomenon arenumerous, but it has proven particularly advantageous for treatingwounds. Regardless of the etiology of a wound, whether trauma, surgery,or another cause, proper care of the wound is important to the outcome.Treatment of wounds or other tissue with reduced pressure may becommonly referred to as “negative-pressure therapy,” but is also knownby other names, including “negative-pressure wound therapy,”“reduced-pressure therapy,” “vacuum therapy,” and “vacuum-assistedclosure,” for example. Negative-pressure therapy may provide a number ofbenefits, including migration of epithelial and subcutaneous tissues,improved blood flow, and micro-deformation of tissue at a wound site.Together, these benefits can increase development of granulation tissueand reduce healing times.

There is also widespread acceptance that cleansing a tissue site can behighly beneficial for new tissue growth. For example, a wound can bewashed out with a stream of liquid solution, or a cavity can be washedout using a liquid solution for therapeutic purposes. These practicesare commonly referred to as “irrigation” and “lavage” respectively.

While the clinical benefits of negative-pressure therapy and irrigationare widely known, the cost and complexity of negative-pressure therapyand irrigation therapy can be a limiting factor in its application, andthe development and operation of negative-pressure systems, components,and processes and irrigation therapy systems, components, and processescontinues to present significant challenges to manufacturers, healthcareproviders, and patients.

BRIEF SUMMARY

New and useful systems, apparatuses, and methods for irrigating a tissuesite in a negative-pressure therapy environment are set forth in theappended claims. Illustrative embodiments are also provided to enable aperson skilled in the art to make and use the claimed subject matter.For example, a system for irrigating a tissue site is described. Thesystem may include a tissue interface configured to be placed adjacentto the tissues site and a sealing member configured to be placed overthe tissue interface to form a sealed space. The system may includenegative-pressure source configured to be fluidly coupled to the sealedspace. The system may also include an irrigation valve having a housingand a piston disposed in the housing. The piston may form a fluid inletchamber and a fluid outlet chamber. The housing may have a fluid inletthat may be coupled to the housing and configured to fluidly couple thefluid inlet chamber to a fluid source, and a fluid outlet that may becoupled to the housing and configured to fluidly couple the fluid outletchamber to the sealed space. A piston passage may extend through thepiston and fluidly coupling the fluid inlet chamber and the fluid outletchamber. A biasing member may be coupled to the piston to bias theirrigation valve to a closed position. The negative-pressure source isconfigured to move the piston between the closed position and an openposition to draw fluid to the sealed space.

In another embodiment, an irrigation valve is described. The irrigationvalve may include a valve body having a valve inlet and a valve outlet.The valve body may form a chamber having a plunger positioned in thechamber to form an inlet chamber in fluid communication with the valveinlet and an outlet chamber in fluid communication with the valveoutlet. A bore may extend through the plunger and be in fluidcommunication with the inlet chamber and the outlet chamber. A springmay be positioned to bias the plunger away from the valve outlet to aclosed position.

In yet another embodiment, a method for controlling irrigation of atissue site is described. A tissue interface may be placed adjacent tothe tissue site, and the tissue interface and the tissue site may becovered to form a sealed space. An irrigation valve may be fluidlycoupled to the sealed space and a fluid source may be fluidly coupled tothe irrigation valve. Negative pressure may be supplied to theirrigation valve through the tissue interface to open a fluid inlet ofthe irrigation valve and draw irrigation fluid to the tissue sitethrough a fluid outlet of the irrigation valve.

In still another embodiment, a method for operating an irrigation valveis described. A fluid source may be fluidly coupled to a fluid inlet ofthe irrigation valve and a negative-pressure source may be fluidlycoupled to a fluid outlet of the irrigation valve. Negative pressure maybe supplied from the negative-pressure source to the fluid outlet of theirrigation valve. The negative pressure may draw a piston of theirrigation valve toward the fluid outlet to open a fluid inlet of theirrigation valve and may draw fluid through a passage of the piston andthe fluid outlet of the irrigation valve.

Objectives, advantages, and a preferred mode of making and using theclaimed subject matter may be understood best by reference to theaccompanying drawings in conjunction with the following detaileddescription of illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of an example embodiment of atherapy system 100 that can irrigate a tissue site in accordance withthis specification;

FIG. 2A is a schematic sectional view illustrating additional detailsthat may be associated with an example embodiment of an irrigation valveof the therapy system 100 of FIG. 1 ;

FIG. 2B is a perspective view illustrating additional details that maybe associated with an example embodiment of a piston of the irrigationvalve of FIG. 2A;

FIG. 3 is a schematic sectional view illustrating additional details ofthe irrigation valve of FIG. 2A in a high-flow position; and

FIG. 4 is a schematic sectional view illustrating additional details ofthe irrigation valve of FIG. 2A is a low-flow position.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The following description of example embodiments provides informationthat enables a person skilled in the art to make and use the subjectmatter set forth in the appended claims, but may omit certain detailsalready well-known in the art. The following detailed description is,therefore, to be taken as illustrative and not limiting.

The example embodiments may also be described herein with reference tospatial relationships between various elements or to the spatialorientation of various elements depicted in the attached drawings. Ingeneral, such relationships or orientation assume a frame of referenceconsistent with or relative to a patient in a position to receivetreatment. However, as should be recognized by those skilled in the art,this frame of reference is merely a descriptive expedient rather than astrict prescription.

FIG. 1 is a simplified functional block diagram of an example embodimentof a therapy system 100 that can provide negative-pressure therapy andirrigation to a tissue site in accordance with this specification. Thetherapy system 100 may include a dressing and a negative-pressuresource. For example, a dressing 102 may be fluidly coupled to anegative-pressure source 104, as illustrated in FIG. 1 . In someembodiments, the negative-pressure source 104 may be fluidly coupled tothe dressing 102 by a fluid interface, such as a connector 106. Adressing generally may include a cover and a tissue interface. Thedressing 102, for example, can include a cover 108, and a tissueinterface 110. The therapy system 100 may also include a fluidcontainer, such as a container 112, coupled to the dressing 102 and tothe negative-pressure source 104.

In some embodiments, the therapy system 100 may also provide irrigationof the tissue site. In some embodiments, the therapy system 100 mayinclude a fluid source and an irrigation valve. For example, the therapysystem 100 may include a fluid source 114 fluidly coupled to anirrigation valve 116. The irrigation valve 116 may be fluidly coupled tothe dressing 102 with a fluid interface, such as a connector 118.

In general, components of the therapy system 100 may be coupled directlyor indirectly. For example, the negative-pressure source 104 may bedirectly coupled to the container 112 and indirectly coupled to thedressing 102 through the container 112. Components may be fluidlycoupled to each other to provide a path for transferring fluids (i.e.,liquid and/or gas) between the components.

In some embodiments, for example, components may be fluidly coupledthrough a tube. A “tube,” as used herein, broadly refers to a tube,pipe, hose, conduit, or other structure with one or more lumina adaptedto convey a fluid between two ends. Typically, a tube is an elongated,cylindrical structure with some flexibility, but the geometry andrigidity may vary. In some embodiments, components may additionally oralternatively be coupled by virtue of physical proximity, being integralto a single structure, or being formed from the same piece of material.Coupling may also include mechanical, thermal, electrical, or chemicalcoupling (such as a chemical bond) in some contexts.

In operation, the tissue interface 110 may be placed within, over, on,or otherwise proximate to a tissue site. The cover 108 may be placedover the tissue interface 110 and sealed to tissue near the tissue site.For example, the cover 108 may be sealed to undamaged epidermisperipheral to a tissue site. Thus, the dressing 102 can provide a sealedtherapeutic environment proximate to a tissue site, substantiallyisolated from the external environment, and the negative-pressure source104 can reduce the pressure in the sealed therapeutic environment.Negative pressure applied across the tissue site through the tissueinterface 110 in the sealed therapeutic environment can inducemacrostrain and microstrain in the tissue site, as well as removeexudates and other fluids from the tissue site, which can be collectedin container 112 and disposed of properly.

The fluid mechanics of using a negative-pressure source to reducepressure in another component or location, such as within a sealedtherapeutic environment, can be mathematically complex. However, thebasic principles of fluid mechanics applicable to negative-pressuretherapy are generally well-known to those skilled in the art, and theprocess of reducing pressure may be described illustratively herein as“delivering,” “distributing,” or “generating” negative pressure, forexample.

In general, exudates and other fluids flow toward lower pressure along afluid path. Thus, the term “downstream” typically implies a position ina fluid path relatively closer to a negative-pressure source, andconversely, the term “upstream” implies a position relatively furtheraway from a negative-pressure source. Similarly, it may be convenient todescribe certain features in terms of fluid “inlet” or “outlet” in sucha frame of reference. This orientation is generally presumed forpurposes of describing various features and components of therapysystems herein. However, the fluid path may also be reversed in someapplications (such as by substituting a positive-pressure source for anegative-pressure source) and this descriptive convention should not beconstrued as a limiting convention.

The term “tissue site” in this context broadly refers to a wound ordefect located on or within tissue, including but not limited to, bonetissue, adipose tissue, muscle tissue, neural tissue, dermal tissue,vascular tissue, connective tissue, cartilage, tendons, or ligaments. Awound may include chronic, acute, traumatic, subacute, and dehiscedwounds, partial-thickness burns, ulcers (such as diabetic, pressure, orvenous insufficiency ulcers), flaps, and grafts, for example. The term“tissue site” may also refer to areas of any tissue that are notnecessarily wounded or defective, but are instead areas in which it maybe desirable to add or promote the growth of additional tissue. Forexample, negative pressure may be used in certain tissue areas to growadditional tissue that may be harvested and transplanted to anothertissue location.

“Negative pressure” generally refers to a pressure less than a localambient pressure, such as the ambient pressure in a local environmentexternal to a sealed therapeutic environment provided by the dressing102. In many cases, the local ambient pressure may also be theatmospheric pressure at which a tissue site is located. Alternatively,the pressure may be less than a hydrostatic pressure associated withtissue at the tissue site. Unless otherwise indicated, values ofpressure stated herein are gauge pressures. Similarly, references toincreases in negative pressure typically refer to a decrease in absolutepressure, while decreases in negative pressure typically refer to anincrease in absolute pressure.

A negative-pressure source, such as the negative-pressure source 104,may be a reservoir of air at a negative pressure, or may be a manual orelectrically-powered device that can reduce the pressure in a sealedvolume, such as a vacuum pump, a suction pump, a wall suction portavailable at many healthcare facilities, or a micro-pump, for example. Anegative-pressure source may be housed within or used in conjunctionwith other components, such as sensors, processing units, alarmindicators, memory, databases, software, display devices, or userinterfaces that further facilitate negative-pressure therapy. While theamount and nature of negative pressure applied to a tissue site may varyaccording to therapeutic requirements, the pressure is generally a lowvacuum, also commonly referred to as a rough vacuum, between −5 mm Hg(−667 Pa) and −500 mm Hg (−66.7 kPa). Common therapeutic ranges arebetween −75 mm Hg (−9.9 kPa) and −300 mm Hg (−39.9 kPa).

The tissue interface 110 can be generally adapted to contact a tissuesite. The tissue interface 110 may be partially or fully in contact withthe tissue site. If the tissue site is a wound, for example, the tissueinterface 110 may partially or completely fill the wound, or may beplaced over the wound. The tissue interface 110 may take many forms, andmay have many sizes, shapes, or thicknesses depending on a variety offactors, such as the type of treatment being implemented or the natureand size of a tissue site. For example, the size and shape of the tissueinterface 110 may be adapted to the contours of deep and irregularshaped tissue sites.

In some embodiments, the tissue interface 110 may be a manifold. A“manifold” in this context generally includes any substance or structureproviding a plurality of pathways adapted to collect or distribute fluidacross a tissue site under negative pressure. For example, a manifoldmay be adapted to receive negative pressure from a source and distributethe negative pressure through multiple apertures across a tissue site,which may have the effect of collecting fluid from across a tissue siteand drawing the fluid toward the source. In some embodiments, the fluidpath may be reversed or a secondary fluid path may be provided tofacilitate delivering fluid across a tissue site.

In some illustrative embodiments, the pathways of a manifold may bechannels interconnected to improve distribution or collection of fluidsacross a tissue site. For example, cellular foam, open-cell foam,reticulated foam, porous tissue collections, and other porous materialsuch as gauze or felted mat generally include pores, edges, and/or wallsadapted to form interconnected fluid pathways. Liquids, gels, and otherfoams may also include or be cured to include apertures and flowchannels. In some illustrative embodiments, a manifold may be a porousfoam material having interconnected cells or pores adapted to uniformly(or quasi-uniformly) distribute negative pressure to a tissue site. Thefoam material may be either hydrophobic or hydrophilic. In onenon-limiting example, a manifold may be an open-cell, reticulatedpolyurethane foam such as GranuFoam® dressing available from KineticConcepts, Inc. of San Antonio, Texas.

In an example in which the tissue interface 110 may be made from ahydrophilic material, the tissue interface 110 may also wick fluid awayfrom a tissue site, while continuing to distribute negative pressure tothe tissue site. The wicking properties of the tissue interface 110 maydraw fluid away from a tissue site by capillary flow or other wickingmechanisms. An example of a hydrophilic foam is a polyvinyl alcohol,open-cell foam such as V.A.C. WhiteFoam® dressing available from KineticConcepts, Inc. of San Antonio, Tex. Other hydrophilic foams may includethose made from polyether. Other foams that may exhibit hydrophiliccharacteristics include hydrophobic foams that have been treated orcoated to provide hydrophilicity.

The tissue interface 110 may further promote granulation at a tissuesite when pressure within the sealed therapeutic environment is reduced.For example, any or all of the surfaces of the tissue interface 110 mayhave an uneven, coarse, or jagged profile that can induce microstrainsand stresses at a tissue site if negative pressure is applied throughthe tissue interface 110.

In some embodiments, the tissue interface 110 may be constructed frombioresorbable materials. Suitable bioresorbable materials may include,without limitation, a polymeric blend of polylactic acid (PLA) andpolyglycolic acid (PGA). The polymeric blend may also include withoutlimitation polycarbonates, polyfumarates, and capralactones. The tissueinterface 110 may further serve as a scaffold for new cell-growth, or ascaffold material may be used in conjunction with the tissue interface110 to promote cell-growth. A scaffold is generally a substance orstructure used to enhance or promote the growth of cells or formation oftissue, such as a three-dimensional porous structure that provides atemplate for cell growth. Illustrative examples of scaffold materialsinclude calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites,carbonates, or processed allograft materials.

In some embodiments, a sealing member, such as the cover 108 may providea bacterial barrier and protection from physical trauma. The cover 108may also be constructed from a material that can reduce evaporativelosses and provide a fluid seal between two components or twoenvironments, such as between a therapeutic environment and a localexternal environment. The cover 108 may be, for example, an elastomericfilm or membrane that can provide a seal adequate to maintain a negativepressure at a tissue site for a given negative-pressure source. In someexample embodiments, the cover 108 may be a polymer drape, such as apolyurethane film, that is permeable to water vapor but impermeable toliquid. Such drapes typically have a thickness in the range of 25-50microns. For permeable materials, the permeability generally should below enough that a desired negative pressure may be maintained.

An attachment device may be used to attach the cover 108 to anattachment surface, such as undamaged epidermis, a gasket, or anothercover. The attachment device may take many forms. For example, anattachment device may be a medically-acceptable, pressure-sensitiveadhesive that extends about a periphery, a portion, or an entire sealingmember. In some embodiments, for example, some or all of the cover 108may be coated with an acrylic adhesive having a coating weight between25-65 grams per square member (g.s.m.). Thicker adhesives, orcombinations of adhesives, may be applied in some embodiments to improvethe seal and reduce leaks. Other example embodiments of an attachmentdevice may include a double-sided tape, paste, hydrocolloid, hydrogel,silicone gel, or organogel.

In some embodiments, the dressing 102 may also include a fluidinterface, such as the connector 106, configured to fluidly couple thenegative-pressure source 104 to the sealed therapeutic environmentformed by the cover 108. In some embodiments, the fluid interface mayinclude a flange portion that couples to the cover 108 and a portionthat fluidly couples to a tube. In one exemplary embodiment, the fluidinterface may be a T.R.A.C.® Pad or Sensa T.R.A.C.® Pad available fromKinetic Concepts, Inc. of San Antonio, Texas. In other exemplaryembodiments, a tube may be inserted through the cover 108. Such a fluidinterface can allow negative pressure to be delivered to the sealedtherapeutic environment. For example, a fluid interface can provide afluid conductor through the cover 108 to the tissue interface 110. Insome embodiments, a fluid interface can also provide more than one fluidpath through the cover 108 or merge more than fluid conductor into asingle fluid path.

The container 112 is representative of a container, canister, pouch, orother storage component, which can be used to manage exudates and otherfluids withdrawn from a tissue site. In many environments, a rigidcontainer may be preferred or required for collecting, storing, anddisposing of fluids. In other environments, fluids may be properlydisposed of without rigid container storage, and a re-usable containercould reduce waste and costs associated with negative-pressure therapy.

The fluid source 114 is representative of a container, canister, pouch,or other fluid storage component, which can be used to manage anirrigation fluid to be provided to a tissue site. In some embodiments,the fluid source 114 may be an intravenous (IV) bag suspended from anintravenous pole. In other embodiments, the fluid source 114 may beanother fluid storage device positioned proximate to a tissue site. Insome embodiments, the fluid source 114 may be positioned verticallyabove a tissue site. In other embodiments, the fluid source 114 may bepositioned vertically level or below a tissue site.

In some embodiments, the dressing 102 may also include a fluidinterface, such as the connector 118, configured to fluidly couple theirrigation valve 116 to the sealed therapeutic environment formed by thecover 108. In some embodiments, the fluid interface may include a flangeportion configured to couple the connector 118 to the cover 108. Inother exemplary embodiments, a tube may be inserted through the cover108 without the connector 118. Such a fluid interface can allow fluid tobe delivered to the sealed therapeutic environment. For example, a fluidinterface can provide a fluid conductor through the cover 108 to thetissue interface 110. In some embodiments, a fluid interface can alsoprovide more than one fluid path through the cover 108 or merge morethan fluid conductor into a single fluid path.

Irrigation therapy may provide a continuous or near continuous supply offluids to a tissue site. The fluids may flow across a tissue site andremove undesired products of the healing process. For example,irrigation therapy may help remove necrotic tissue, bacteria, exudates,dirt, or other substances from the tissue site. Generally, saline may beused as an irrigation fluid. Saline can provide good infection control,and if appropriate, additional fluids may be added to the saline or maybe provided in combination with saline to address specific issues of aparticular tissue site.

Irrigation therapy does not generally include a dwell time; instead,fluids are preferably moved across the tissue site continuously.Continuous movement of fluid can use a large amount of fluid and canrequire frequent changing of waste fluid containers. Irrigation therapymay also require use of dedicated equipment, and systems for providingirrigation therapy may not interact well with other therapy systems. Forexample, an irrigation therapy system may require a positive-pressurepump to move irrigation fluid to and across a tissue site. If irrigationtherapy is paired with negative-pressure therapy, operation of thepositive-pressure pump can interfere with negative-pressure therapy ifnot managed properly. A clinician may be required to closely monitor theoperation of both systems to ensure that both therapies are properlyprovided. The need for dedicated irrigation therapy equipment can alsoprove problematic in mobile situations, such as in emergency medicalvehicles or small trauma centers. Space may be at a premium and manyusers may choose to only provide one type of therapy device.Consequently, many patients may not receive beneficial irrigationtherapy.

The therapy system 100 can significantly decrease the cost andcomplexity of integrating irrigation therapy with negative-pressuretherapy. In some embodiments, the therapy system 100 can enable anegative-pressure source to drive irrigation fluids, and permit thecontrol of irrigation without interfering with negative-pressuretherapy.

For example, in some embodiments, the negative-pressure can actuate theirrigation valve 116, drawing fluid through the irrigation valve 116 andto the tissue site. By using the therapy system 100 to actuateirrigation therapy, the rate at which fluids can be provided to a tissuesite may be controlled by the application of negative-pressure.Furthermore, the irrigation valve 116 can provide irrigation therapywithout requiring additional supplemental devices, such as a dedicatedirrigation pump.

FIG. 2A is a schematic sectional view illustrating additional detailsthat may be associated with some example embodiments of the irrigationvalve 116. In some embodiments, the irrigation valve 116 may include avalve body, such as a housing 200. The housing 200 may be tubular. Insome embodiments, the housing 200 may form a portion of an exterior ofthe irrigation valve 116. If the housing 200 is tubular, the housing 200may be an annular wall having an interior. In some embodiments, thehousing 200 may have an axis 201.

In some embodiments, the irrigation valve 116 may include an end wall203 and a conical end 206. The end wall 203 may be coupled to an end ofthe housing 200 and may close the end of the housing 200. The end wall203 may prevent fluid communication through the end of the housing 200.The conical end 206 may be coupled to the housing 200 on an end that isopposite the end wall 203. In some embodiments, the conical end 206 mayhave a base 205 and an apex 209. The base 205 of the conical end 206 maybe coupled to an end of the housing 200, and the conical end 206 mayextend away from the housing 200 to the apex 209. In some embodiments,the conical end 206 may be coaxial with the axis 201. The end wall 203and the conical end 206 may form boundaries of the interior of thehousing 200. In some embodiments, the interior formed by the housing200, the end wall 203, and the conical end 206 may be fluidly isolatedfrom the ambient environment.

In some embodiments, the irrigation valve 116 may also include a valveinlet, such as a fluid inlet 202 and a valve outlet, such as a fluidoutlet 204. The fluid inlet 202 may be coupled to the end wall 203. Thefluid inlet 202 may be offset from the axis 201. For example, the fluidinlet 202 may be coupled to the end wall 203 radially outward from theaxis 201 and proximate to the housing 200. In other embodiments, thefluid inlet 202 may be coaxial with the axis 201. In some embodiments,the fluid inlet 202 may be a fluid port or other device configured toallow fluid communication through the end wall 203. The fluid inlet 202may be configured to be coupled to a fluid source, such as the fluidsource 114, and to provide fluid communication between the fluid sourceand the interior of the housing 200. The fluid outlet 204 may be coupledto the apex 209 of the conical end 206 and may be coaxial with the axis201. The fluid outlet 204 may be a fluid port or other device configuredto allow fluid communication through the conical end 206. The fluidoutlet 204 may be configured to be fluidly coupled to a sealed spaceadjacent a tissue site or to a negative-pressure source, such as thenegative-pressure source 104.

In some embodiments, the irrigation valve 116 may include a plunger orpiston, such as a piston 207. The piston 207 may be disposed in theinterior of the housing 200 and form a first chamber, such as an outletchamber or fluid outlet chamber 210. The piston 207 may have a cap, suchas a head 208, a plunger rod or piston rod, such as a rod 212, and aplug or valve member 214. The head 208 may be a disc having an outerdiameter substantially equal to an inner diameter of the housing 200. Insome embodiments, one or more o-rings, piston rings, or sealing ringsmay be disposed around the head 208 to seal the head 208 to the housing200. The head 208 may have a first surface facing the end wall 203 and asecond surface facing toward the conical end 206. In some embodiments,the head 208 may reciprocate within the housing 200. For example, thehead 208 may be in contact with the end wall 203 in a first position, asshown in FIG. 2A. In some embodiments, the head 208 may prevent fluidcommunication through the fluid inlet 202 if the head 208 is in contactwith the end wall 203.

The rod 212 may be coupled to the head 208. In some embodiments, the rod212 may be a cylinder and be coaxial with the axis 201. The rod 212 mayhave a first end coupled to the head 208 and extend from the head 208toward the conical end 206. A second end of the rod 212 may be oppositethe head 208. In other embodiments, the rod 212 may not be a cylinderand may not be coaxial with the axis 201.

The valve member 214 may be coupled to the second end of the rod 212.The valve member 214 may be a cone having a base 215 coupled to the rod212 and extend away from the second end of the rod 212 to an apex 219.In some embodiments, a diameter of the base 215 of the valve member 214may be substantially equal to a diameter of the rod 212. In someembodiments, the valve member 214 may be coaxial with the axis 201 andmay have a length parallel to the axis 201.

In some embodiments, a bore or passage, such as a piston passage 216,may extend through the piston 207. For example, the piston passage 216may pass through the head 208, extend through the rod 212, and terminateproximate to a side of the valve member 214. In some embodiments, thepiston passage 216 may be coaxial with the axis 201 through the head208. The piston passage 216 may remain coaxial with the axis 201 throughthe rod 212. In some embodiments, a portion of the piston passage 216may be coaxial with the axis 201 through at least a portion of the valvemember 214. The piston passage 216 may include an elbow that turns thepiston passage 216 away from the axis 201. For example, as shown in FIG.2A, the piston passage 216 may include an elbow that turns the pistonpassage 216 toward a side of the valve member 214 that connects the base215 of the valve member 214 with the apex 219 of the valve member 214.In some embodiments, the piston passage 216 may terminate proximate tothe base 215 of the valve member 214. In other embodiments, the pistonpassage 216 may not be coaxial with the axis 201. For example, thepiston passage 216 may be located radially outward from the axis 201 ata location of the head 208 having a larger diameter than the outerdiameter of the rod 212. In some embodiments, the piston passage 216 maynot include an elbow, but may extend through the piston 207 at an angle.

The piston passage 216 may be separated or offset from the fluid inlet202. For example, if the piston passage 216 is coaxial with the axis201, the fluid inlet 202 may be positioned in the end wall 203 so thatthe fluid inlet 202 is not coaxial with the axis 201. In anotherexample, if the fluid inlet 202 is coaxial with the axis 201, the pistonpassage 216 may be positioned to be radially separated from the axis201. In some embodiments, if the head 208 of the piston 207 is incontact with the end wall 203, the piston passage 216 may not be influid communication with the fluid inlet 202. In some embodiments, thepiston passage 216 may be sized to accommodate a particular flow rate ata particular pressure. In some embodiments, the piston passage 216 maybe sized to accommodate a flow rate of about 10 cubic centimeters(cc)/minute when a pressure differential between the ends of the pistonpassage 216 is about 75 millimeters of mercury (mm Hg). In someembodiments, the piston passage 216 may have a diameter between about 1millimeter (mm) and about 2 mm.

FIG. 2B is a perspective view illustrating additional details of anexample embodiment of the piston 207. In some embodiments, another fluidpassage, such as a groove 218, may be formed in the valve member 214.The groove 218 may extend from the apex 219 of the valve member 214toward the base 215 of the valve member 214. In some embodiments, thegroove 218 may have a length that is less than the length between theapex 219 and the base 215 of the valve member 214. As shown in FIG. 2B,the piston passage 216 may terminate in a side of the valve member 214.

Referring to FIG. 2A, the fluid outlet chamber 210 may be a variablevolume chamber disposed in the interior of the housing 200. In someembodiments, the housing 200 may define a portion of the fluid outletchamber 210. The fluid outlet chamber 210 may extend from the head 208to the fluid outlet 204. In some embodiments, the fluid outlet chamber210 may be coextensive with the interior of the housing 200. Forexample, if the head 208 is in contact with the end wall 203, the fluidoutlet chamber 210 may be coextensive with the interior of the housing200 between the head 208 and the fluid outlet 204. If the head 208 movesfrom contact with the end wall 203, the volume of the fluid outletchamber 210 may change in response.

In some embodiments, the irrigation valve 116 may include a biasingmember, such as a spring 220. The spring 220 may be disposed in thefluid outlet chamber 210 of the housing 200 between the second surfaceof the head 208 and the conical end 206. In some embodiments, the spring220 may have a first end proximate to the conical end 206. A second endof the spring 220 may be adjacent to the head 208. In some embodiments,the rod 212 may be inserted into a center of the spring 220, and thespring 220 may at least partially circumscribe the rod 212. In someembodiments, the spring 220 may be coaxial with the axis 201.

As shown in FIG. 1 , the irrigation valve 116 may be fluidly coupled toa fluid source 114 and a negative-pressure source 104 through a dressing102. Referring to FIG. 2A, the fluid source 114 may be fluidly coupledto the fluid inlet 202. In some embodiments, the fluid in the fluidsource 114 may exert a fluid pressure on the piston 207 through thefluid inlet 202. For example, the fluid source 114 may be positioned ata vertically higher elevation than the irrigation valve 116 and exert afluid pressure on the piston 207 through the fluid inlet 202 due to theforce of gravity. The fluid pressure may urge the head 208 toward theconical end 206. In other embodiments, the fluid pressure exerted by thefluid in the fluid source 114 may be negligible.

In some embodiments, the fluid outlet 204 may be fluidly coupled to anegative-pressure source, such as the negative-pressure source 104. Iffluid is drawn from the fluid outlet chamber 210 through the fluidoutlet 204, such as by operation of the negative-pressure source 104, anegative pressure may be developed in the fluid outlet chamber 210. Thenegative-pressure in the fluid outlet chamber 210 may generate a cause adifferential pressure across the head 208 that exerts a force on thehead 208 that urges the head 208 toward the conical end 206. The forceof negative-pressure in the fluid outlet chamber 210 and fluid pressurethrough the fluid inlet 202 may be referred to as a differential force.

As shown in FIG. 2A, the irrigation valve 116 may be in a first positionor a closed position. The head 208 may be in contact with the end wall203, preventing fluid communication into the interior of the housing 200through the fluid inlet 202. The differential force may urge the head208 toward the conical end 206; however, the differential force may beinsufficient to overcome the spring force of the spring 220. Generally,a spring, such as the spring 220 may exert a force that is proportionalto a distance the spring is moved from a relaxed position. In someembodiments, the spring 220 may have a length X₁ if the irrigation valve116 is in the closed position.

FIG. 3 is a schematic sectional view illustrating additional detailsthat may be associated with some embodiments of the irrigation valve116. As shown in FIG. 3 , the irrigation valve is in a second position.The second position may also be referred to as an open position, a fullfluid flow position, or a high flow position. In the high flow position,the differential force may exceed the spring force of the spring 220,and the head 208 may move toward the conical end 206. As the head 208moves toward the conical end 206, a second chamber or inlet chamber,such as a fluid inlet chamber 222, may be formed in the housing 200. Thefluid inlet chamber 222 may be bounded by the head 208, the end wall 203and the housing 200. In some embodiments, the fluid inlet chamber 222may form a portion of the interior of the housing 200. The fluid inletchamber 222 may extend from the head 208 to the end wall 203. The fluidinlet chamber 222 may be in fluid communication with the fluid inlet 202and the piston passage 216. Fluid entering the fluid inlet 202 may flowthrough the fluid inlet chamber 222 to the piston passage 216. In someembodiments, the fluid may flow through the piston passage 216 to thefluid outlet chamber 210. Fluid may then flow from the fluid outletchamber 210 through the fluid outlet 204 and to a tissue site.

Generally, the flow rate through the piston passage 216 may be based inpart on the negative pressure developed in the fluid outlet chamber 210.For example, the piston passage 216 may have a diameter between about 1mm and about 2 mm and permit fluid flow at about 10 cubiccentimeters/minute (cc/minute) if a negative pressure of about 75 mm Hgis developed in the fluid outlet chamber 210. In other embodiments, thediameter of the piston passage 216 may be varied to increase or decreasethe fluid rate as needed for a given pressure.

Movement of the head 208 toward the conical end 206 may also compressthe spring 220. For example, the spring 220 may be compressed from thelength X₁ to a length X₂ that is less than the length X₁. If thenegative pressure in the fluid outlet chamber 210 is decreased, forexample, if the dressing 102 is removed from the tissue site, the spring220 may exert a force on the head 208 that urges the head 208 toward theend wall 203. In some embodiments, the spring 220 may urge the head 208into contact with the end wall 203 if the negative pressure decreasesbelow about 65 mm Hg, preventing fluid communication through the fluidinlet 202.

FIG. 4 is a schematic sectional view illustrating additional detailsthat may be associated with some embodiments of the irrigation valve116. As shown in FIG. 4 , the piston 207 is in a third position, whichmay also be referred to as a low flow position. In some embodiments, thenegative pressure developed in the fluid outlet chamber 210 may furthercompress the spring 220 between the head 208 and the conical end 206. Asshown in FIG. 4 , the spring 220 may be compressed to have a length X₃that is less than the length X₂. In some embodiments, movement of thehead 208 may move the valve member 214, coupled to the head 208 throughthe rod 212, into the fluid outlet 204. Positioning of the valve member214 into the fluid outlet 204 may partially block fluid flow through thefluid outlet 204. In some embodiments, if the valve member 214 is in aseated position in the fluid outlet 204, the groove 218 may have alength sufficient to provide a fluid path through the fluid outlet 204.In some embodiments, the groove 218 may have a diameter between about0.2 mm and about 0.3 mm. Fluid may flow through the groove 218 at about0.5 cc/minute when a reduced pressure of about 125 mm Hg is developed inthe fluid outlet chamber 210.

In some embodiments, the irrigation valve 116 may be actuated by thenegative-pressure source 104 to provide irrigation therapy. Thenegative-pressure source 104 may be turned on and set to provide anintermittent therapy. The negative-pressure source 104 may remove fluidfrom the tissue site to develop and maintain the negative pressure atthe tissue site at about 125 mm Hg. During this time, the negativepressure developed at the tissue site may be communicated to the fluidoutlet chamber 210 through the fluid outlet 204. In response, the piston207 may move to the low flow position of FIG. 4 . Fluid flow through thegroove 218 and the fluid outlet 204 to the tissue site may be about 0.5cc/minute. In some embodiments, the negative-pressure source 104 maymaintain the negative pressure at about 125 mm Hg for about 60 minutes,providing about 30 cubic centimeters (cc) of fluid to the tissue site.

In some embodiments, the negative-pressure source 104 may stopdeveloping negative-pressure for about 10 minutes. During this timeperiod, the negative pressure at the tissue site and the fluidly coupledfluid outlet chamber 210 may decrease. In response, the spring 220,compressed to the length X₃, may exert a force on the head 208 of thepiston 207, moving the head 208 toward the end wall 203 and removing thevalve member 214 from the fluid outlet 204. Fluid may flow into thetissue site at about 10 cc/minute, providing about 100 cc of fluid tothe tissue site.

If the pressure at the tissue site, or the fluid outlet 204 is atambient pressure, for example, if the dressing 102 is removed from thetissue site, or if there is a leak preventing the development ofnegative pressure at the tissue site. The spring 220, compressed fromthe length X₁ to either the length of X₂ in FIG. 3 or X₃ in FIG. 4 , maymove the head 208 back into contact with the end wall 203, preventingfluid flow through the fluid inlet 202.

The negative-pressure source 104 and the irrigation valve 116 cooperateto provide continual flow of irrigation fluid through the irrigationvalve 116 to the tissue site throughout the high-flow state of FIG. 3and the low-flow state of FIG. 4 . The negative-pressure developed bythe negative-pressure source 104 interacts with the irrigation valve 116and the groove 218 and piston passage 216 of the piston 207 to provide acontinual flow of irrigation fluid.

The systems, apparatuses, and methods described herein may providesignificant advantages. For example, the irrigation valve 116 may permitthe application of an irrigation fluid to a wound from a simple,potentially disposable device, using existing vacuum therapy systems.The irrigation valve may also be used in the home and in emergingmarkets with little oversight. The irrigation valve may also be usedwith existing negative-pressure therapy system and devices withoutrequiring a dedicated irrigation therapy pump.

The irrigation valve can provide controlled irrigation in a compactdevice. For example, the irrigation valve may be lightweight and sizedto provide a known fluid flow for given conditions. A trauma center oremergency vehicle may have multiple irrigation valves sized to providedifferent flow rates at a same negative-pressure so that irrigation canbe provided based on the needs of the tissue site. Furthermore, theirrigation valves may be made from materials that make disposal costeffective.

The irrigation valve may also be orientation insensitive. For example,the irrigation valve may operate as intended regardless of the positionof the irrigation valve or the orientation of the irrigation valverelative to the force of gravity.

While shown in a few illustrative embodiments, a person having ordinaryskill in the art will recognize that the systems, apparatuses, andmethods described herein are susceptible to various changes andmodifications. Moreover, descriptions of various alternatives usingterms such as “or” do not require mutual exclusivity unless clearlyrequired by the context, and the indefinite articles “a” or “an” do notlimit the subject to a single instance unless clearly required by thecontext.

The appended claims set forth novel and inventive aspects of the subjectmatter described above, but the claims may also encompass additionalsubject matter not specifically recited in detail. For example, certainfeatures, elements, or aspects may be omitted from the claims if notnecessary to distinguish the novel and inventive features from what isalready known to a person having ordinary skill in the art. Features,elements, and aspects described herein may also be combined or replacedby alternative features serving the same, equivalent, or similar purposewithout departing from the scope of the invention defined by theappended claims.

What is claimed is:
 1. A system for treating a tissue site, comprising:a manifold configured to contact the tissue site; a drape configured tobe positioned over the manifold to form a sealed space; a first fluidinterface configured to be fluidly coupled to the sealed space and afluid source; a second fluid interface configured to be fluidly coupledto the sealed space and a negative pressure source; and an irrigationvalve fluidly coupled to the first fluid interface, the irrigation valvecomprising: a housing having an end wall, a conical base and a variablevolume chamber; a fluid inlet coupled to the end wall and configured tobe fluidly coupled to the fluid source; a fluid outlet coupled to theconical base and configured to be coupled to the negative pressuresource; a plunger disposed in the housing, the plunger having a head, arod having a first end coupled to the head and a second end coupled to avalve member; a fluid passage disposed inside the plunger and extendingthrough the plunger from the head to the valve member of the plunger,the fluid passage fluidly coupled to the fluid inlet and the fluidoutlet; and a spring configured to at least partially surround the rodand bias the plunger.
 2. The system of claim 1, wherein the first fluidinterface comprises a flange configured to couple the first fluidinterface to the drape.
 3. The system of claim 1, wherein the secondfluid interface comprises a flange configured to couple the second fluidinterface to the drape.
 4. The system of claim 1, wherein the firstfluid interface comprises a tube configured to be inserted through thedrape and be fluidly coupled to the sealed space.
 5. The system of claim1, wherein the second fluid interface comprises a tube configured to beinserted through the drape and be fluidly coupled to the sealed space.6. The system of claim 1, wherein the variable volume chamber comprisesa fluid inlet chamber fluidly coupled to the fluid inlet and a fluidoutlet chamber fluidly coupled to the fluid outlet.
 7. The system ofclaim 1, wherein the spring is configured to bias the plunger between afirst position, a second position, and a third position.
 8. The systemof claim 7, wherein a length of the spring is greater in the firstposition than a length of the spring in the second position and a lengthof the spring in the third position.
 9. The system of claim 7, wherein alength of the spring in the second position is greater than a length ofthe spring in the third position.
 10. The system of claim 1, furthercomprising a groove disposed in a side of the valve member configured tofluidly couple the fluid outlet to the variable volume chamber if thevalve member is positioned in the fluid outlet.
 11. The system of claim10, wherein the groove has a diameter between about 0.2 mm and about 0.3mm.
 12. The system of claim 10, wherein the groove is sized toaccommodate a flow rate of about 0.5 cc/minute at a negative pressure ofabout 125 mm Hg.
 13. The system of claim 1, wherein the fluid passagehas a diameter between about 1 mm to about 2 mm.
 14. The system of claim1, wherein the fluid passage is sized to accommodate a flow rate ofabout 10 cc/minute at a negative pressure of about 75 mm Hg.
 15. Thesystem of claim 1, wherein the fluid source comprises an intravenousfluid bag.
 16. The system of claim 1, wherein the fluid is saline.